Other reasons for the increase were the number of cats running away after being temporarily rehomed during the summer holidays, and owners going into hospital, she said.
Chairman Rob Sewell said although about 39 cats and kittens were transferred to the Wellington SPCA a few weeks ago, there were still too many in the Masterton centre.
"When we are getting to 10 or 12 we are actually getting quite full - 12 cats in one room is getting quite busy."
As well as causing the animals to become frustrated, having more cats in one room could also increase the risk of disease.
It broke his heart to see the animals penned up, Mr Sewell said. "It's all about getting them a loving home."
ADOPTION OFFER:
- The discounted rate of $50 applies to cats aged 18 months and upwards.
- All the cats are flea and worm treated, de-sexed and microchipped.
- The offer runs until February 1.
- The Wairarapa SPCA is located at 299 Ngaumutawa Rd, Masterton.
Opening hours are 9am - 12am and 3pm - 4pm, seven days a week.